Continuous dyeing of textile



May 25, 1943. G. F. WOMBLE Re. 23,004

CONTINUOUS DYEING OF TEXTILE MATERIALS Original Filed Oct. 21, 1 9415INVENTOR. I five/m F womb]:

Wneys Mani Pooskn fivx Reissued May 25, 1948 CONTINUOUS DYEING OFTEXTILE MATERIALS Glenn F. Womble, Danville, Va., assignor to Dan RiverMills, Incorporated, a corporation of Virginia Original No. 2,396,908,dated March 19, 1946, Serial No. 507,211, October 21, 1943. Applicationfor reissue March 15, 1947, Serial No.

6 Claims.

This invention relates to the process of continuous dyeing of textilematerials with vat dyestuffs.

The object of the invention is to provide a rapid economical andcontinuous method of vat dyeing, obtaining results comparable in depthof shade, fastness properties and appearance, to the products of the oldand well known pigment-pad method, a two step process commonly used inthe practice of dyeing vat colors of medium and heavy shades.

Dyeing with vat" dyestuffs is accomplished by reducing them chemicallyby a suitable reducing agent such as sodium hydrosulphite, to the leucocondition and dissolving them by means of a suitable alkali such assodium hydroxide (commonly known as caustic soda). In this conditionthey are taken up by the affinity of the various fibers constituting thematerial, rinsed with water and subsequently oxidized by the oxygen ofthe air, or chemical oxidizing agents such as sodium perborate, sodiumbichromate, and acetic acid, hydrogen peroxide, and numerous others;

rinsed again and usually soaped to remove any loose particles ofdyestuii, to develop the shade, and increase the fastness properties andgiven a final rinsing with water to remove the soap.

The usual methods of dyeing vat colors on piece goods are straight jig,.pigmentqaad jig, and continuous dyeing.

In straight-jig dyeing, the reduced and dissolved color is added to abath containing the necessary amounts of reducing and dissolvingchemicals contained in a rectangular trough, on which two rollers, whichmaybe revolved around the longitudinal axis with corresponding drivingand braking arrangements, are fixed. The fabric, which is provided atboth ends with end cloths, is wound in the open width in a stretchedcondition onto one of these rollers which is fixed above the jig. Forthe purpose of dyeing, the fabric is alternately wound oflf one roller(delivery roller) in the open width and in a stretched condition, passedthrough the dye-liquor by means of two or three guide rollers which arefixed in the jig and wound on to the other roller (receiving roller).Four to eight of such passages of the material are necessary toaccomplish the desired shade. By similar passages of the materialthrough a rinse, oxidizing bath, soaping bath, and.

a final rinse, the dyeing operation is completed. The average jig willproduce approximately five hundred to one thousand yards in four hours.

In pigment-pad jig" dyeing, the dry undyed material is impregnated inthe open width with very undesirable a dispersion of vat pigment, i. e.,undissolved color in water, from a stock tank and passed through apadder, i. e., squeezed through two rubber covered rollers or a metalroller and a rubber covered roller with the bottom roller being driven,thus delivering the material to a batching arrangement which rolls upthe material on a wooden shell or core in the form of a jig-roll whichin turn is loaded on the jig. The jig bath or rectangular box beforementioned in describing straight-jig dyeing, is charged with thenecessary reducing and dissolving chemicals and from this step on theprocess is identical with straight-jig dyeing.

In continuous vat dyeing (as heretofore practiced) the dry undyedmaterial is fed through a padder as described under pigmentpad dyeing,but instead of being impregnated with a dispersion of pigment in water,the dyestuff is previously dissolved with the usual caustic soda (orother alkalis) and reducing agents, usually sodium hydrosulphite and fedto. the padder from a stock tank. Then in order to complete the dyeingwhich requires time, the material is passed through a booster box orboxes, containing rollers arranged to allow goods to remain in them fromthirty seconds to five minutes, depending on depth of shade desired,which is, or are, charged with the quantity of dissolved dyestuffnecessary to sustain the depth of shade afiorded by the stock feed, andthe necessary amounts of alkali and reducing agents; then throughrinsing, oxidizing, rinsing, soaping and rinsing box or boxesrespectively, the material being held in the open width during theentire operation,

Some of the disadvantages of previous mentioned methods are:

1. In dyeing by the straight-jig method, a few yards of lead line, orend cloths, have to be sewn to each end of the jig roll to protect thegood cloth from too much exposure in the dye bath while reversing same.The material always suffers from improper penetration, leaving thedyestuff precipitated on the surface, giving a appearance and inferiorfastness properties. Because of the .dyestu-fis being added atintervals, and the fact that in a combination of dyestuffs, the affinityof the individual dyestuffs usually vary widely, the shading as a ruleis bad. When the dyeing operation is finished, there is always asizeable amount of color and chemicals left over that cannot be usedagain and is lost. Too, there is quite a bit of unneces- 3 sary laborinvolved and time consumed as compared to continuous dyeing.

2. In dyeing by the pigment-pad method, the fastness properties andappearance of the finished goods are satisfactory, but it is a two stepmethod, which consumes too much time and labor, has dyestuff andchemicals left over to be dumped down the drain, and usually bad shadingproperties. As in the case of straightjig dyeing, end cloths have to besewn on and at the end of the operation removed, an operation expensivein wasted material and labor.

3. The most recent method, continuous vat dyeing, is far more economicalfrom the cost standpoint, i. e. cost of chemicals and dyestuffs, laborinvolved and shading properties. But the depth of shade economicallyobtainable at a reasonable cost, the requisite fastness properties, thedesirable solid or smooth appearance of the material are all limited tolight or at most medium shades.

The depth of shade obviously depends upon the concentration of thefeeding liquor stored in a stock tank or tanks. Heretofore, the dyestuifwas dissolved in the stock tank or before bein added to the stock tank,and applied to the textile in the dissolved condition. The concentrationand consequently the depth of shade is limited by the solubility of theparticular dyestuff in question. Furthermore even if the dyestufi issufiiciently soluble, a high concentration cannot be used as it requiresmore time than is available for the dyestuff to be absorbed by thetextile material with theresult that the unabsorbed portion is washedoff in the booster and rinse boxes.

Furthermore, nearly all vat dyestuffs are unstable in solution and breakdown more or less rapidly on standing. If for any reason the continuousoperation is interrupted for any considerable length of time the reducedand dissolved dyestuff in the feed tank must be thrown away and a newlot made up. Finally, it is quite impossible to foresee the exact amountof dyestuif which must be reduced and dissolved for a. given lot oftextile material. Any excess dye solution must be thrown away. Due tothe fact that the stability of a reduced vat solution is influenced bythe temperature atwhichit is maintained and the length of time it isheld in solution before using, frequently there are large quantities ofexpensive dyestuffs lost due to delays which are inevitable when a shadeis being matched for the first time.

In the processes contemplated by the present invention, there is acontinuous dyeing of textile materials with vat dyestufis which areapplied in the form of a water dispersion of the pigment and dried orsemi-dried to fix the pigment on and within the fabric. The pigment issubsequently reduced, that is, dissolved in the common caustic alkaliand reducing agents such as sodium hydrosu-lphite, and precipitated byoxidation on or in the fibers, all in one operation.

In the drawing:

Fig. 1A is a line diagram of dyeing circuit.

Fig. 1B shows the end of this circuit. By the novel method hereindescribed of a continuous pigment padding of the material and asubsequent drying or semi-drying, and developing in one operation, thisinvention overcomes the disadvantages listed in the foregoing methods.Also it enables the dyer to salvage any quantity of stock solution leftover.

a portion of the In accordance with the present process the vat colorsare applied in pigment form dispersed or suspended in water. This isdone by a two roll padder which has an immersion box T and which isindicated generally at l2. As previously described a padder consists oftwo rubber covered rollers or a metal roller and a rubber covered rollerwith the bottom roller being driven. The material is fed to the padder[2 from a scray II. The immersion box T is supplied with the pigment inproper suspension in water. As the material passes through the rolls ofpadder [2, it is squeezed to the point that the moisture retained isreduced to from 50 to 75% of the weight of the fabric. It is then passedthrough a dryer or hot flue l3 such as the Andrews-Goodrich type ofdryer.

It has been found that in applying the vat colors in this Way thepigment is evenly distributed since the pigment itself has little or noafiinity for the neps, that is, the distribution is not affected by thethick or thin places or other irregularities that might be present andlater cause disagreeable effects in the finished goods.

With the pigment applied in this way it can be rapidly dissolved anddyed simultaneously. This dissolving and dyeing is preferablyaccomplished through a three roller padder l4 arranged in tandem withbooster boxes l5 and I6 which also contain reducing and dissolvingchemicals.

The immersion box B of padder [4 holds the reducing and dissolvingchemicals for the padder I4. One or more of the booster boxes l5 and [6can be used depending on the time required for fixing the particulardye. The three roller padder arrangement is preferably in conjunctionwith the booster boxes since the extra squeezes to which the cloth issubjected cause better penetration of the goods. It is found that only ashort time, usually from one to two minutes, is needed to dissolve anddevelop the shade. This is probably due to the fact that previous dryinghas driven off the water used in applying the pigment, thus leaving thematerial in a condition in which it will quickly absorb the solution ofcaustic alkalis and reducing agents. Furthermore, the vat pigment isleft after drying in a condition in which the maximum amount of surfacearea is exposed and it is already heated to or above the reducingtemperature, thus facilitating rapid solution and dyeing action.

After passing rapidly through the reducing bath, that is, consuming onlythe time usually necessary for pastel shades dyed by regular methods,the dyed material is rinsed, oxidized, soaped,

if necessary, and rinsed according to facilities available for usualpractice of continuous vat dyeing.

The pleasing and unexpected results found are:

(1) The ability to reduce (or dissolve) and dye simultaneously andcontinuously at rates of speed comparable to the usual methods fordyeing light shades.

(2) Production of medium and heavy shades having a smooth appearancefree from the usual disagreeable heavy dyed neps and irregular surfacedeposits which are usually present as a result of trying to dye sameshades by the usual reduced pad continuous dyeing methods. This processis especially adapted to the use on heavy and closely woven goods suchas Windbreaker poplins and heavy twills of the types used for army wear,allowing unusual speeds of one hundred yards or more per minute.

Example 1 Mercerized bleached cotton majestic poplin which weighs .36lb. per yard'is dyed a medium shade of vat khaki at the rate of 100yards per minute on a continuous dyeing machine by the followingprocedure:

Pigment padded on two roll pad l2 with a feed liquor of 1.49 oz. pergal. Indanthrene Brown BRA paste, .926 oz. per gal. Calcoloid Yellow GCDpaste and .29 oz. per gal. Calcoloid Grey BD paste; passed through hotfiue l3 (thereby dried); through three roll pad l4 containing requisitequantities of reducing and dissolving ing reducing and dissolvingchemicals; skip second booster box l6; rinsed; soaped and rinsed throughremaining wash boxes I! to 22 and finally folded into box 23.

Indanth'rene Brown BRA is listed in the AATCC year book as Pr. 118;Calcoloid Yellow GCD has a color index 1095; Calcoloid Grey ED is aproduct of the Calco Chemical Company.

Example 2 Mercerized boiled out cotton wind resistant" poplin asspecified by U. S Government is dyed vat olive drab at the rate of 90yards per minute on same continuous vat dyeing machine as used inExample 1 as follows:

Pigment padded on two roll pad l2 with a feed liquor containing 2.16ozs. per gallon Ponsol Brown AGG double paste, 2.26 ozs. per gallonPonsol Olive GGL paste and 1.02 ozs. per gallon Ponsol Golden Orange 4Gpaste; passed through hot flue I3 and semi-dried; through three roll padl4 containing-requisite quantities of reducing and dissolving chemicals;through first and second booster boxes I5 and I6; through rinse,oxidizing, soap, hot wash and rinse boxes IE to 22 thereby completingthe dyeing operation.

Ponsol Brown AGG, Ponsol Olive GGL, and Ponsol Golden Orange 4G areproducts of the E. I. du Pont de Nemours 81 Co., Inc.

Example 3 Mercerized boiled out cotton herringbone twill as specified byU. S. Government is dyed continuously, the vat O. D. No. '7 shade at therate of 80 yards per minute on the same machine as Exampie 2 by paddingthe following vat pigments on two roll pad l2:

Ounces Indanthrene Olive TA paste 4.34 Carbanthrene Khaki'2G paste 5.84Indanthrene Olive Green BA paste 1.63

Indanthrene Olive TA is a product of General Aniline Works and is soldby General Dye Corporation; Carbanthrene Khaki 2G and Indanthrene OliveGreen BA are listed in AATCC year book as Pr. 122 and 293, respectively.

chemicals; through first booster box l5 containis defined asincludingnotonly'wide and narrow fabrics, but also single yarns andcords.

I'clalm: V 1. Those steps in the method of continuous vat dyeing solidcolors on textile materials which compriseapplying to the textile apigment from an unthickened water-suspension or dispersion,

' removing the water by squeezing and heating to leave the pigment inthe textile, and immediately subjecting the textile previously dried byheating to an alkaline reducing agent, and squeezing said fabric toobtain penetration of said reducing agent and contact with the pigmentsin tho fabric.

2. Those steps in the method of solid color dyeing of one continuouspiece of textile material in one operation with vat dyestuffs, whichcomprise applying to the textile a fluid, unthickened, water dispersionof pigment, squeezing and drying by heating to remove a substantialportion of the water from the textile during movement of the textilewithout disturbing the pigment on the textile, immediately subjectingthe heat dried textile for a relatively short period of time to analkaline reducing bath maintained at substantially constant andrelatively high concentration, and then subjecting the continuous lengthof textile to a squeezing action after such reducing bath to obtainthorough penetration of said reducing agent and contact with thepigments in the fabric.

3. Those steps in the method of continuous dyeing solid colors ontextile materials with vat dyestuifs which comprise applying to thetextile an unthickened water dispersion of vat pigment, subjecting thetextile to a uniform squeezing action, drying by heating the textile,immediately subjecting the heat dried textile to a bath of reducing anddissolving chemicals, squeezing said chemicals onto the pigment treatedcloth to initiate the action between the fiber and the dyestuff, andthen subjecting said cloth to one or more baths of reducing anddissolving chemicals.

4. In a continuous dyeing process for vat dyeing solid colors on acontinuous piece of textile material, those steps which includedispersing throughout the fabric vat dye pigments from the unthickenedaqueous suspension, removing the greater portion of such liquid bysqueezing, and then drying by heating, immediately thereafter but onlyfor a relatively short period of time subjecting such heated fabric toone or more baths of an alkalinereducing agent, the heat in said fabricassisting in maintaining the temperature of the alkaline reducing agent,and squeezing said fabric to obtain penetration of said alkalinereducing agent and contact with the dry pigments in the fabric.

5. In a continuous dyeing process for vat dyeing solid colorson acontinuous piece of textile material, those steps which includedispersing throughout the fabric vat dye pigments from an unthickenedwater suspension, removing the great portion of said liquid by squeezingso that the moisture retained is reduced to less than 75% of the weightof the fabric, and then drying by heating, and immediately but for only.a relatively short period of time subjecting the continuously movingheat dried fabric to one or more baths of an alkaline reducing agentmaintained at substantially constant and. relatively high concentration,the speed of movement of said dry fabric into and through said highconcentration bath being at the rate of over fifty yards per minute.

6. Those steps in the method of dyeing solid colors on one continuouspiece of textile material 7 in one operation with vat dyestuffs whichcomprise, dispersing throughout the textile vat pigments from anunthickened aqueous suspension, removing a substantial portion of theliquid by squeezing, and then drying by heating, and continuing themovement of the textile immediately through a bath of an alkalinereducing agent of constant and relatively high concentration, the heatof the fabric assisting in maintaining the temperature of said bath, thedeveloping of the shade of the textile before rinsing requiringapproximately two minutes or less.

GLENN F. WOMBLE.

REFERENCES CITED The following references are of record in the file ofthis patent:

Number UNITED STATES PATENTS Name Date Schlegel July 14, 1908 Villigeret a1. Oct. 3, 1922 Macadam May 7, 1929 Baker Nov. 6, 1934 Lubs July 4,1939 Williams Apr. 30, 1940 Wedler June 18, 1940 Williams Dec. 12, 1944Amer. Dyestufl Reporter, Nov.

OTHER REFERENCES 15, 1937, pages

